This invention generally relates to retractable projection screens. Moreover, it pertains specifically to a reinforced retractable projection screen with tab tensioning. The border material of the screen is textile or fabric and is attached to the screen at the edges in a non-overlapping manner. The retractable projection screen also has an adjustable coupling device and strips of metal.
Projection screens are typically made of vinyl or some other elastic material that both reflects a projected image and may or may not provide acoustic transparency. Vinyl is also typically used for retractable projection screens because it is easily folded or rolled. However, this ability to fold and roll means that retractable projection screen may also exhibit distortions or waviness if improperly handled or stored or if the loads on the screen are distributed in an uneven fashion. A common method to improve the flatness and reduce the distortion and noticeable waves in a retractable projection screens is through the use of a tab tensioning system. Current tab tensioning systems commonly employ the use of a weight bar along the bottom to pull the projection screen down in a uniform manner. Additionally, the sides of the screen have tabs that project horizontally out that a cable is passed through. The cable, when taut, creates an arc shape along the sides of projection screen. In this manner, the projection screen is held flat.
Traditionally, retractable projection screens are made using a vinyl screen material that may or may not be supported by fabric. If the vinyl screen lacks reinforcing fiber threads either within or behind the vinyl, it is commonly called non-reinforced vinyl or non-reinforced screen material. Non-reinforced vinyl projection screens require a tensioning system, because vinyl is not mechanically strong enough to hold a weight bar, and will stretch down and deform over time. A tab tensioning system distributes the forces from the weight bar evenly around the screen material and prevents the deformation of the vinyl screen.
The borders for a non-reinforced vinyl screen are typically differentiated from the screen, or image surface, and painted black. The black paint absorbs some of the spill over projection light so this stray light is not reflected back in a distracting way to the audience viewing the projected image. Additionally, the black paint helps to hide any tension tabs from view. Paint is used because it does not significantly add to the thickness of the screen as it retracts. Differences in thickness between the visual screen area and the black border area cause the vinyl to deform along the sides of the screen resulting in significant distortion waves, which are visible after retraction and may not be corrected by the tab tensioning system. The tensioning tabs are typically attached to the screen within the black border area to avoid any minor tension deformities, and so that the tabs are not easily visible.
Retractable vinyl projection screens that have internal fiber reinforcement or fiber reinforcement backing typically do not have tab tensioning systems. These projection screens are referred to as reinforced vinyl projection screens or reinforced material projection screens. The reinforced vinyl projection screen is capable of mechanically holding the weight of the bottom weight bar, or batten, without having to distribute the tensioning forces horizontally via a tab tensioning system. As such, a tab tension system is not required. A reinforced vinyl projection screen, to a certain extent, resists the distortion forces and does not benefit as much as a non-reinforced vinyl projection screen from a costly multi-tab tensioning system. However, reinforced vinyl projection screens can distort over time, and could benefit from a simple and inexpensive tab tensioning system.
Reinforced vinyl projection screen surfaces are often mechanically similar to common blackout cloth, or they are made from woven vinyl coated threads similar to a solar shade material. Importantly, this latter type of material provides acoustic transparency. The borders for these screens are typically masked from the image or projection surface and painted black for the same benefits as described above. Projection screen manufacturers prefer paint over fabric border materials because paint does not significantly add to the thickness of the screen as it retracts and thus cause distortions.
The black paint used to absorb the spill over light from the projection is not an ideal solution. The ideal border material for a retractable projection screen would have infinite light absorption. Although no such material exists yet, generally, a textured textile or cloth, such as velvet, velveteen, velour, felt, a flocked material, or a suede material will absorb many times more light than black paint. These high light absorbing textured textiles, typically dyed black, are the preferred choice for fixed-frame projection screen designs. The disadvantage of overlaying a textile or cloth boarder material onto the vinyl screen of a retractable projection screen is that the material is much thicker than black paint, and inevitably causes a non-uniform roll-up of the projection screen. When the projection screen is unrolled the distortions caused by the different thicknesses are often visible and may become permanent over time.
Thus, there is a need in the art for a reinforced projection screen with a textile or cloth border that has a uniform thickness across the entire width of the projection screen and that is adaptable to an inexpensive tab tensioning system.